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ACT Protocols for Wave Measurement Systems
July 2012
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Hence, based upon this recognized reality, the Directional Waverider DWR- MkIII manufactured
by Datawell Oceanographic Instruments will be used as the reference/standard for the deep and
intermediate water wave evaluations. The DWR-MkIII has established a long and impressive
history of side-by-side comparisons with other wave measurement systems and in particular with
the Long Linear Array at FRF. Based on this history of comparison, the DWR-MkIII was
selected as the “reference standard” for the purposes of these Technology Test and Evaluation
protocols. The Waverider buoy uses Hippy heave-pitch-roll sensors to measure wave direction
and energy and carry two horizontal accelerometers for measuring north/south and east/west
displacements. This translational system uses pitch-roll to correct the buoy movement to a fixed
x-y-z reference frame, giving it a better signal-to-noise ratio than buoys that use pitch-roll
directly to estimate directional wave properties. The Waverider
is the primary wave system
operated by the Coastal Data Information Program, located at the Scripps Institution of
Oceanography (CDIP/SIO). The Waverider has been shown to effectively measure waves with
periods from 1/6 to 30 seconds with an error of no more than 3%. (see
http://cdip.ucsd.edu/?nav=documents&sub=index&units=metric&tz=UTC&pub=public&map_st
ati=1,2,3&xitem=gauge#buoys)
As Task 1 of the Wave Test and Evaluation Plan, the Datawell Waverider Buoy will be verified
for deep water at the Conoco Phillips off-shore platform Ekofisk in the North Sea in 70 meters
water depth. The Ekofisk Laser Array (LASAR) has been in operation since February of 2003
and carries four vertically pointed lasers for wave measurement in a square configuration. The
downward looking Optech lasers are positioned on bridges Flare North and Flare South, in the
platform complex. The laser instruments determine the height of the sea surface at a fixed
horizontal position by measuring the time from the emission of a light pulse to its detection after
reflection at the air-water interface.
Location of EKOFISK in the North Sea (Norwegian Meteorological Institute).